In laparoscopic surgery, a single hole-type surgery through which the surgery is performed by inserting a plurality of treatment tools such as forceps or optical devices through an incision has been performed. The surgery method has a great cosmetic advantage since only an incision remains on the body surface of a patient. Generally, the incision is formed in the umbilicus in order to prevent the incision from being conspicuous after the surgery.
In recent years, exclusive instruments for inserting a plurality of treatment tools in an incision has been developed (refer to Patent Documents 1 and 2). These instruments include a cylindrical retractor main body that holds the incision in an opened state and a lid-like converter having a plurality of small holes (ports) through which the treatment tools are respectively inserted.
Meanwhile, in the laparoscopic surgery, it is necessary to take an excised organ (excised tissue) outside the body. Since the excised tissue cannot pass through the port, in a case of taking out an excised tissue larger than the inner diameter of the port, the forceps holding the excised tissue have been pulled out together with the retractor main body from the incision. In addition, in a case where cancer is suspected to be present in an organ, in general, the excised tissue is collected in a collection bag in the abdominal cavity, and then, the excised tissue is taken out by pulling the collection bag together with the retractor main body from the incision in order to prevent implantation of the cancer. However, the work for pulling out the retractor main body from the incision imposes a large burden on the patient. In particular, in a case of excising a plurality of diseased areas and repeatedly taking out the tissues, it is necessary to install and remove the retractor main body many times with respect to the incision, which imposes a large burden on the patient.
In contrast to the above, in the instruments disclosed in Patent Documents 1 and 2, the converter is detachable from the retractor main body. For this reason, when taking out the excised tissue, it is possible to pull out the forceps or the collection bag through an opening of the retractor main body, the opening having a large diameter, by removing the converter from the retractor main body while placing the retractor main body in the incision. Accordingly, it is unnecessary to repeatedly attach the retractor main body to and detach the retractor main body from the abdominal wall even in the case of taking out the large excised tissue or collection bag to the outside the body. For this reason, it is possible to promptly perform excision with a small burden on the patient.
In the instrument disclosed in Patent Document 1, as shown in FIG. 1 thereof, the converter is installed in a manner such that a projection is locked to an engagement groove by rotating the converter (valve plate) around an axis with respect to the retractor main body (holder main body). In addition, in the instrument, as shown in FIG. 5(b) or FIG. 6(b) of Patent Document 1, the projections and the ports are disposed to have equal angular intervals (120 degree intervals). For this reason, the arrangement position of the ports with respect to the retractor main body can be always kept constant without particularly considering the attachment angle of the converter.
In addition, in the instrument of Patent Document 2, as shown in FIG. 10 (FIG. 11) or FIG. 16 (FIG. 17) thereof, it is possible to detachably install a converter (20), to which a plurality of ports (25 to 28) are provided, by pushing the converter to a retractor main body (2) at an arbitrary angle. Specifically, as shown in FIG. 10 of Patent Document 2, a mode of installing a connector base (80), around which a plurality of elastic projections (91) are formed, in a ring (6) in a snap manner, and a mode of inserting an O ring (53) in an engaging ring (54) as shown in FIG. 16 thereof are disclosed.